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Date: Tue, 15 Jun 2010 13:31:32 +0200
From: Kevin Wolf <kwolf@redhat.com>
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Subject: Re: [Qemu-devel] Re: [PATCH v2 1/2] qcow2: Simplify image creation
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To: Stefan Hajnoczi <stefanha@gmail.com>
Cc: qemu-devel@nongnu.org

Am 15.06.2010 13:08, schrieb Stefan Hajnoczi:
> On Tue, Jun 15, 2010 at 11:36 AM, Kevin Wolf <kwolf@redhat.com> wrote:
>> +    /*
>> +     * And now open the image and make it consistent first (i.e. increase the
>> +     * refcount of the cluster that is occupied by the header and the refcount
>> +     * table)
>> +     */
>> +    BlockDriver* drv = bdrv_find_format("qcow2");
>> +    assert(drv != NULL);
>> +    ret = bdrv_open(bs, filename, BDRV_O_RDWR | BDRV_O_NO_FLUSH, drv);
>> +    if (ret < 0) {
>> +        goto out;
>> +    }
> 
> Here I think we should really return directly on error.
> bdrv_delete(bs) doesn't work since bs isn't initialized when
> bdrv_open() fails.

I did consider returning directly here at first, but decided against it
because usually you expect that a function that uses some goto does so
consistently. Also, I noticed later that returning directly we would
leak the BlockDriverState which is malloc'd in bdrv_file_open.

bs should still be initialized at this point and bs->drv = NULL after
the bdrv_close() above, so that bdrv_delete(bs) will just free the
BlockDriverState.

Kevin